NASA's shuttle Endeavour is on track for a planned weekend launch toward the International Space Station, mission managers said Tuesday.

Endeavour is slated to blast off at 7:17 a.m. EDT (1117 GMT) Saturday morning from NASA's Kennedy Space Center in Cape Canaveral, Fla., and preparations are going smoothly, launch test director Charlie Blackwell-Thompson told reporters in a mission briefing today.

"All of our systems are in great shape," she said. "I have no issues to report. The STS-127 flight crew, Endeavour, and the launch team are all ready to proceed."

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The shuttle is slated for a 16-day construction flight to the International Space Station to deliver the last segment of the Japanese Kibo laboratory, a porch-like experiment platform that will be attached to the lab's outer hull.

Five spacewalks are planned to install the new porch, as well as new solar array batteries and spare parts.

Endeavour's seven-member crew, led by veteran astronaut Mark Polansky, arrived at the shuttle's seaside launch site late Monday at 11:53 p.m. EDT (0353 GMT). The official launch countdown is set to begin tomorrow at 9:00 a.m. EDT (1300 GMT).

"We're absolutely thrilled to be down here in preparation for Saturday's launch of Endeavour," Polansky said after landing in Florida last night.

So far, even the weather looks to cooperate for this weekend's morning launch.

"The weather forecast for our launch day is 80 percent go," Blackwell-Thompson said. "Certainly it's a very promising forecast."

If Endeavour is unable to launch Saturday, NASA can try again June 14 or June 15.

Then the shuttle program must stand down to allow the liftoff of the Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (LCROSS) to proceed as planned June 17.

If the shuttle is unable to launch in June, NASA would have to wait until mid July, when sun angles at the space station are favorable, to try again.

Endeavour's STS-127 mission is NASA's third shuttle flight of the year and comes on the heels of a successful repair mission to the Hubble Space Telescope last month.

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